Role of Stress in Expression of Mammalian Secondary Hormones (Eicosanoids) in Red Algae: The overall objective of this proposal is to establish that specific red algal secondary natural products, eicosanoids are involved in stress response (signaled by or correlated with the production of stress proteins) in these organisms. Eicosanoids are biologically active molecules that are involved in many basic human metabolic functions, playing important roles in mammalian homeostasis where they are present in virtually every mammalian tissue and body fluid and where they exert a broad spectrum of physiological activities. Enzyme systems responsible for eicosanoid metabolism evolved 100's of millions of years prior to their appearance in mammals. Establishment that eicosanoids evolved as stress management compounds, and that their role has been conserved through evolution would provide a functional homology with one of its major roles in animals where the lipoxygenase- mediated formation of leukotrienes and lipoxins serves as a signal to initiate stress responses within the organisms. The objectives will be carried out by culturing the target species, Murrayella periclados, in the laboratory and examining the time course of stress protein expression, lipoxygenase enzyme induction and subsequent eicosanoid expression. Stress protein identification will employ 2 dimensional SDS PAGE. Eicosanoid concentrations will be measured using ELISA assays. A molecular probe for Murrayella lipoxygenase will be developed and the resultant gene or gene fragment will be utilized to produce polycolona antibodies. The antibodies will then be used to follow lipoxygenase induction following stress conditions utilizing ELISA assays.